Type of mattress to buy from your range

I like firm mattress like they have in hotels. I don't like foam ones that feel hot. I need back support and my current mattress gives me neck and back pains. I am 5 '2 in height and 140 lbs. I require a king sized mattress. I can look at up to 1500 pounds for a mattress. I want to know how I can make sure the mattress will not be too hard and I want it cool to the feel.